1. Field of the Invention
This invention generally relates to processing video and more specifically to enhancing video.
2. Description of the Related Art
The sharing of video content on websites has developed into a worldwide phenomenon, supported by dozens of websites. Many thousands of videos are posted every day, and this number is increasing as the tools and opportunities for capturing video become easier to use and more widespread. Millions of people watch the posted videos.
Uploaded videos are often of poor visual quality because many videos are captured under poor lighting conditions or using inexpensive cameras. Particularly, the contrast of uploaded videos is often low, making foreground objects difficult to distinguish from other objects and from the background. Thus, there is a need to process the uploaded videos to enhance contrast and make the videos more visually appealing.
Conventional image enhancement techniques such as histogram stretching or histogram equalization improve image quality by determining a histogram of pixel luminance values for an individual image frame, and stretching the histogram over an increased range of luminance values. These conventional image enhancement techniques can be extended to video by applying image enhancement independently to each individual frame of the video. However, conventional video enhancement techniques often corrupt video transition effects and introduces unwanted artifacts into the video. In addition, conventional video enhancement techniques are not well-suited for large scale applications such as video sharing, because of the substantial computational burden involved in processing every frame of video individually. Therefore, there is a need for a video enhancement technique that is well suited for large scale applications.